One vertex per element, one color per generator, with an edge from x to x·s.
(2,3)(5,6)(7,10)(8,9)(11,12)(13,14)(15,17)(16,24)(18,21)(19,22)(20,26)(23,28)(25,27) involution — undirected(1,2,4,3)(6,9)(10,12)(13,14)(15,18)(16,25)(17,21)(19,22)(20,28)(23,26)(24,27)(1,3,4,2)(13,15,18,22,19,21,17,14)(16,23,27,25,28,24,26,20)(5,7,8,11)(6,10,9,12)(13,16,17,26,19,28,18,27)(14,20,21,24,22,25,15,23)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.